I'm planning to install a small FPV camera to my Crazyflie 2.0 and I need to know the quad's power output.
I've been looking around on several online sources (even within Bitcraze) and couldn't find this information.

I do not understand if you are after the radio or power supply power so I can answer both .

Crazyflie 2.0 has a radio power amplifier that can output up to 20dBm/100mW on 2.4GHz.

If what you are asking for is the electrical power supply, you can get regulated 3V on VCC for up to 100mA and unregulated VCOM (it is the battery voltage) for up to 1A. You most likely want VCOM in your case.